1. Field of the Invention
The invention relates to acid compositions with a high content of active ingredients for the treatment of water and/or the descaling of installations comprising at least one water-soluble carboxylic polymer, at least one strong acid bascially of mineral origin, possibly at least one metallic salt of a bivalent cation and possibly specific agents such as corrosion inhibitors, biocide agents, perfumes, etc.
2. Discussion of the Background
For a long time the necessity of treating waters intended to supply industrial and/or domestic installations or waste in the form of aqueous effluents has been apparent to one skilled in the art.
Where natural waters and/or aqueous media are intended for industrial or domestic uses, they generally contain certain alkaline earth metals, solubilized in a saline form, such as calcium and magnesium. The compounds of these metals have the property of being insoluble and of becoming deposited in the form of mineral encrustations on the surfaces of the industrial or domestic installations which contain them, such as heat exchangers for heating (furnaces for production of hot water or steam), heat exchangers for cooling, steam turbines, steam pumps and condensers, evaporators, air conditioning units, heating circuits for individual or collective housing, sanitary installations in glazed earthenware.
Consequently, it has been shown to be necessary to prevent or to reduce to the maximum the formation of mineral encrustations on the surfaces of the industrial or domestic installations (in contact with the water) which are too often injurious, for example to the capacity of heat exchanges of the surfaces of heat exchangers or to the rate of flow of fluids so as to prevent or at least limit the risks of blocking the installations and to maintain them in good operating condition.
This is why the skilled artisan has already proposed aqueous compositions for the treatment of waters containing a low concentration of various well-known active agents, such as carboxylic copolymers with a low molecular weight, which agents slow the formation of scale resulting from the presence in the water of alkaline earth ions and which disperse the particles of clays, scale and metallic oxides which are present, and which also contain acids providing the regulation of the pH and assisting in dissolving of the scale formed, and finally also contain corrosion inhibitors, for example phosphoric acid, benzotriazole, intended to protect the metallic surfaces of the installations.
In this regard, a method has already been described (FR No. 2,231,778) for inhibiting the corrosion of metals in an aqueous medium consisting of maintaining in said medium a concentration of at least 5 ppm of a composition composed of zinc and at least one polymer with a molecular weight of between 500 and 10,000 selected from the group consisting of polyacrylamide, polyacrylic acid and sodium polyacrylate.
In the same vein, but for descaling and/or cleaning glazed earthenware sanitary installations, treatment compositions have been proposed (FR No. 2,469,450) which contain water-soluble polyacrylic acids, organic acids such as acetic, citric or lactic acids, a corrosion-inhibiting agent and, finally, additives such as perfumes, coloring agents and biocides.
Similarly, to limit the formation of scale and fight against the corrosion phenomena of industrial and/or domestic installations of a metallic type, the use (in an amount of at least 10 ppm) has been indicated (FR No. 2,231,778) of a composition comprising at least one water-soluble polymer having a molecular weight of between 500 and 10,000 and at least one corrosion-inhibiting agent such as phosphoric acid, benzotriazole, or mercaptobenzotriazole as well as a zinc salt.
However, all the acid compositions already recommended for the treatment of waters have a same major disadvantage in common which requires the skilled artisan to prepare and use them at low concentrations. Due to a certain incompatibility between the water-soluble polymer with the low molecular weight and the other agents included in the compositions intended for the treatment of the water, when compositions are prepared with a high concentration of active agents, an imbalance occurs in the shape of a precipitation which renders said compositions unsuitable for the use for which they are intended.
Therefore, since it has been shown to be impossible in use to prepare acid compositions with a high content of active ingredients for the treatment of water without causing the precipitation or at least the partial precipitation of said active ingredients, the skilled artisan has often carried out and still carries out either the simultaneous injection of concentrated solutions containing various active ingredients which are incompatible with one another at such concentrations or even the preparation and use of a diluted aqueous solution, that is with a low concentration of active ingredients. The first method has more disadvantages for the user than the second due to possible errors in the concentrations of active ingredients in the injected solutions and due to the regulation of the speeds of injection of said solutions.
Since then, applicant has shown (FR No. 2,544,722), by improved compositions for the treatment of water containing a carboxylic polymer and a zinc salt, the interest of replacing the acrylic acid polymer with an acrylic acid, methacrylic acid and an itaconic acid terpolymer having a substantially equivalent molecular weight. However, it has been noted during use that these terpolymers were also unsuitable for the preparation of acid compositions with a high content of active ingredients intended for the treatment of waters such as, for example, those containing high concentrations of said terpolymer, a zinc salt and a strong acid such as phosphoric acid or the phosphonic acids and, in addition, other specific agents, because they precipitate when they are incorporated into a medium which has a high concentration of strong acid.
Faced with the economic necessity and the technical requirement of having acid compositions with high concentrations of active ingredients intended for the treatment of industrial or domestic waters and for the cleaning of the corresponding industrial or sanitary installations, applicant, by continuing his research, found and perfected such compositions.